The invention is generally directed to toner and developer compositions, and, more specifically, the present invention is directed to developer and toner compositions containing modified, for example surface treated colloidal silica particles, including the known AEROSILS.RTM. available from Degussa, Inc., and which particles can be selected for toners with rapid admix, excellent flow, and acceptable triboelectrical characteristics. In embodiments, there are provided in accordance with the present invention toner compositions comprised of resin particles, pigment particles, optional charge additives such as quaternary ammonium hydrogen bisulfates, including distearyl methyl hydrogen ammonium bisulfates; distearyl dimethyl ammonium methyl sulfate; alkyl pyridinium halides; metal complexes such as aluminum complexes, reference U.S. Pat. No. 4,845,003, the disclosure of which is totally incorporated herein by reference; TRH, reference U.S. Pat. Nos. 4,758,493 and 4,433,040, the disclosure of which are totally incorporated herein by reference; and more specifically 3,5-di-tertiary-butylsalicylic acid, and its salts; BONTRON E-82.TM.; BONTRON E-84.TM.; BONTRON E-88.TM.; halogenated salicylic acids; LR120.TM., available from Carlit Inc. of Japan, and the like; and modified silica particles, like AEROSILS.RTM. as surface additives. The silica particles can be modified by a process which comprises the coating thereof with components that will, for example, reduce and regulate the moisture content thereof enabling the generation of a higher negative toner tribo and a toner with improved relative humidity resistivity as compared to toners wherein untreated, that is colloidal silicas not subject to the alcohol treatment processes of the present invention, are selected. In embodiments, a number of long chain alcohols can be selected for treating the silica surface. Examples of treating components include long chain aliphatic alcohols, wherein aliphatic is preferably alkyl with from 12 to about 30 carbon atoms. Toners with the aforementioned treated surface additives in embodiments of the present invention possess rapid admix of less than about one minute, extended developer life, stable electrical properties, high image print quality with substantially no background deposits, and improved insensitivity to relative humidity of, for example, from 20 to 80 percent RH. Also, the aforementioned toner compositions usually contain pigment particles comprised of, for example, carbon black, magnetites, or mixtures thereof, cyan, magenta, yellow, blue, green, red, or brown components, or mixtures thereof thereby providing for the development and generation of black and/or colored images. The toner compositions of the present invention in embodiments thereof possess excellent admix characteristics as indicated herein, and maintain their triboelectric charging characteristics for an extended number of imaging cycles, exceeding for example 1,000,000 in a number of embodiments. The toner and developer compositions of the present invention can be selected for electrophotographic, especially xerographic, imaging and printing processes, including full color processes and trilevel color processes.
Illustrated in The Chemistry Of Silica, R. K. Iler, John Wiley and Sons, page 654, 1979, or Dokl. Akad. Nauk USSR, 125, 1247(1959), and in Proceedings Academy Sciences USSR Phys. Chem. Engl. Transl., 114, 421, (1957) is the adsorption of alcohols, such as hexyl alcohol, from carbon tetrachloride on the surface of silicas that were dehydroxylated. The Handbook Of imaging Materials, Edited by Arthur S. Diamond, page 169, 1991, indicates that good flow properties are usually desired and often are critical for toners, and that materials, such as fumed silicas, can be added to the surface of a toner to improve flow, and can improve charge stability of the toner and carrier mixture.
The above prior art relates, for example, to silica gels, which are hydrophilic, and thus sensitive to relative humidity, and further in the above paper Proceedings Academy Science USSR Phys. Chem. Engl. Transl., 114, 421, (1957) it is indicated that the adsorption of long chain alcohols, such as 1-octadecanol, is not effective as they cannot penetrate into the surface of the silica gel. With the present invention, there is formed a layer of hydrocarbon chains on the silica surface, and with the prior art such layers did not form since the alcohol chain was probably not of sufficient length. While not being desired to be limited by theory, it is believed that the hydrocarbon layer based on DSC is formed with the invention processes since the hydroxy groups on the alcohol molecules form hydrogen bonds with the silica surface, and a hydrophobic interaction occurs between the aliphatic chains which bound together by Van der Waals forces and thus enable a substantially permanent protective layer for the silica particles.
Developer compositions with colloidal silica surface components and charge enhancing additives, which impart a positive charge to the toner resin, are known. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of quaternary ammonium salts as charge control agents for electrostatic toner compositions. In this patent, there are disclosed quaternary ammonium compounds with four R substituents on the nitrogen atom, which substituents represent an aliphatic hydrocarbon group having 7 or less, and preferably about 3 to about 7 carbon atoms, including straight and branch chain aliphatic hydrocarbon atoms, and wherein X represents an anionic function including, according to this patent, a variety of conventional anionic moieties such as halides, phosphates, acetates, nitrates, benzoates, methylsulfates, perchlorate, tetrafluoroborate, benzene sulfonate, and the like; U.S. Pat. No. 4,221,856 which discloses electrophotographic toners containing resin compatible quaternary ammonium compounds in which at least two R radicals are hydrocarbons having from 8 to about 22 carbon atoms, and each other R is a hydrogen or hydrocarbon radical with from 1 to about 8 carbon atoms, and A is an anion, for example, sulfate, sulfonate, nitrate, borate, chlorate, and the halogens, such as iodide, chloride and bromide, reference the Abstract of the Disclosure, and column 3; a similar teaching is presented in U.S. Pat. No. 4,312,933, which is a division of U.S. Pat. No. 4,291,111; and similar teachings are presented in U.S. Pat. No. 4,291,112 wherein A is an anion including, for example, sulfate, sulfonate, nitrate, borate, chlorate, and the halogens. There are also described in U.S. Pat. No. 2,986,521 reversal developer compositions comprised of toner resin particles coated with finely divided colloidal silica. According to the disclosure of this patent, the development of electrostatic latent images on negatively charged surfaces is accomplished by applying a developer composition having a positively charged triboelectric relationship with respect to the colloidal silica.
Also, there are disclosed in U.S. Pat. No. 4,338,390, the disclosure of which is totally incorporated herein by reference, developer compositions containing as charge enhancing additives organic sulfate and sulfonates, which additives can impart a positive charge to the toner composition, and AEROSIL.RTM. surface additives. Further, there is disclosed in U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions with resin particles and pigment particles, and as charge enhancing additives alkyl pyridinium compounds AEROSIL.RTM. surface additives. Additionally, other documents disclosing positively charged toner compositions with charge control additives and AEROSIL.RTM. surface additives include U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014; 4,394,433 and 4,560,635 which illustrates a toner with a distearyl dimethyl ammonium methyl sulfate charge additive. One disadvantage associated with the charge additive of the '635 patent resides in its apparent inherent instability in some instances thus rendering it substantially unsuitable as a bulk toner constituent in imaging processes, as the additive can thermally and chemically degrade, and react with other toner components.
Moreover, toner compositions with negative charge enhancing additives and surface additives are known, reference for example U.S. Pat. Nos. 4,411,974 and 4,206,064, the disclosures of which are totally incorporated herein by reference. The '974 patent discloses negatively charged toner compositions comprised of resin particles, pigment particles, and as a charge enhancing additive ortho-halo phenyl carboxylic acids. Similarly, there are disclosed in the '064 patent toner compositions with chromium, cobalt, and nickel complexes of salicylic acid as negative charge enhancing additives. Toners with colloidal silica surface additives are illustrated in U.S. Pat. Nos. 3,590,000 and 3,900,588, the disclosures of which are totally incorporated herein by reference. Also, U.S. Pat. Nos. 5,256,514, and 5,256,575, illustrate negatively charged toners with certain charge additives adsorbed on silica surfaces. The disclosures of each of the aforementioned patents are totally incorporated herein by reference.
There are illustrated in the following copending applications filed concurrently herewith, the disclosures of which are totally incorporated herein by reference: U.S. Ser. No. 234,076, now U.S. Pat. No. 5,451,481, a toner composition comprised of resin, pigment, optional charge additive and a hydrophobic flow aid surface additive comprised of grafted alcoholic silica; and U.S. Ser. No. 234,206, now U.S. Pat. No. 5,397,667, a toner composition comprised of resin, pigment, optional charge additive and a flow aid surface additive comprised of hydrophobic metallized silica of a size diameter of from about 5 to about 40 nanometers, and which silica has been treated with a long chain aliphatic alcohol.